if it is not in there then it is not in there. Modding a BIOS to add things that are not in there could brick your board.
its a Intel Core 2 Duo T5600, so it could do VT but the bios option is hidden by acer because of the marketing concept ...
i did this already ... but they said to me that the bios option is hidden and that they will not release an bios with this function enabled ...
I doubt that Acer ever would make a statement such as "This BIOS feature is hidden ... ... ... " In best case scenario they would just tell you that your hardware is not compatible.
Without the right knowledge it's almost impossible. Anyway you may open your biosfile A2-124.ROM with Phoenix Bios Editor 2.2.0.1....... I did it, you may even emulate the setup, but I didn't find anything about to enable Intel VT....I have to say about Phoenix bioses, they are complex and sometimes they will not properly rebuild after modification....